Download Data/hora: 01/05/2017 13:24:33 Provedor de dados: 31 País: United

Data/hora: 09/06/2017 01:25:48
Provedor de dados: 31
País: United States
Título: Examining Point-Nonpoint Trading Ratios for Acid Mine Drainage Remediation with a
Spatial-Temporal Optimization Model
Autores: Zhao,
Xiaobing; Fletcher,
Jerald J.
Data: 2005-05-17
Ano: 2005
Palavras-chave: Point-nonpoint water quality trading; Trading ratio; Acid mine drainage; Spatial-temporal
optimization; Environmental Economics and Policy.
Resumo: A trading ratio is required for water quality trading that involves nonpoint sources to
compensate for the difficulty of determining nonpoint loadings, the stochastic
characteristics of nonpoint loadings, and the uncertainty inherent in nonpoint source
pollution control strategies. Compensating for risk and uncertainty is one of the primary
justifications that a trading ratio greater than one is commonly considered. However, the
appropriate specific value of a trading ratio remains unclear because of qualitative
differences between point and nonpoint sources. This study addresses a growing concern
with the analytical underpinnings of point/nonpoint trading ratios in water quality trading
programs. This paper considers a basic spatial-temporal optimal control model assuming
that the goal of the decision maker is to maximize ecological services from the watershed
over a 10-year planning horizon given a predetermined budget each year to treat acid
mine drainage problems. The level of pollution is assumed to be known but declining
slightly over time as the acid mine drainage sources evolve. Resources are assumed to be
spent on remediation projects that produce long term but declining treatment results. The
primary goal of the model is to distribute the available resources over the basin by
investing in restoration projects for targeted streams each year that will maximize the
ecological return on this investment. The model reflects both the spatial reality of
variations in flow, in pollution, in treatment, and in the ecological benefits produced and
the intertemporal constraints of limited resources and the inability to move remediation
programs once the initial investment is made. The resulting optimal temporal and spatial
investment strategies are derived from solutions to a mixed integer programming problem
obtained using the GAMS/CPLEX mixed integer programming package. The optimal
results are then manipulated to evaluate trading ratios. A hypothetical acidity trading
scenario is proposed in which a point source (a new coal mine operation subject to TMDL
rules) uses credits generated through remediation projects at other sites from treatment of
nonpoint sources within the same basin over the 10-year planning horizon. The trading
ratio is the ratio of the expected amount of pollutant removed by treating the nonpoint
source divided by the amount of additional pollution allowed from the new point source.
Our results indcate that point/nonpoint trading ratios in proposed trading scenarios greater
than one can be justified. For example, for a point/nonpoint trade between sources in
adjacent stream segments, the appropriate trading ratio is 3.66 (or 3.66 to one). We note
that current regulations give a lower bound for point/nonpoint trading ratio of 1:1. The
upper bound for point/nonpoint trading ratio depends on technical aspects of the relative
costs of treating the point source or treating nonpoint sources and reflects the limit of how
much one is willing to pay for credits. A variety of factors determine trading ratios. First,
to encourage trades with less uncertainty, trades in which the credit seller and buyer are in
close proximity, and in which the credit seller is upstream, lower trading ratios are
recommended. Second, trading ratios should be adjusted to favor trades that contribute to
strategic restoration goals such as the improvement or maintenance of water quality in a
particular basin. Reduced ratios provide incentives to promote the generation of credits in
priority locations. Finally, trading ratios for same-pollutant trades should be lower than
those for cross-pollutant trades. Three separate trading currencies would be used to
account for same-pollutant acid mine drainage trades: pounds of iron, aluminum, and
manganese. There would be little uncertainty in the outcome of a trade if the credit
generator and buyer were affecting the same pollutant. In contrast, cross-pollutant trades
that use a common currency such as ecological indices would be measured based on their
ecological effect, which is one step removed from the actual changes in pollutant loads.
The higher trading ratio required for cross-pollutant trades reflects this greater
uncertainty. All potential trades considered in this study are interspatial trades; trades
occur in the same basin; trades could be cross-pollutant trades within acid mine draiange
and same-pollutant trades as well; and the credit buyer is the new coal mining operation;
credit generators could be government agencies or nonprofit organization; and abandned
mine lands and bond forfeiture sites can be sites where credits are generated.
Tipo: Conference Paper or Presentation
Idioma: Inglês
Identificador: 16471
http://purl.umn.edu/19231
Editor: AgEcon Search
Relação: American Agricultural Economics Association>2005 Annual meeting, July 24-27,
Providence, RI
Selected Paper 136870
Formato: 24
application/pdf